Circuit system for telephone repeating apparatus.



'PATENTEn-AUG. 25, 1908.

y H. E. SHRBEVE. CIRCUIT SYSTEM TOR TELEPHONE. RBTTATTNG APPARATUS.

APPLIGATION FILED MAR. 15. 1907.

narran-syringes learner, onirica.

HERBERT EJSHREEVE, OF N EWTON, MASSACHUSETTS, ASSIGNOR TO AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

Specification of Letters Patent.

Patented Aug. es, 190s.

Application iled. March l5, 1907. Serial No. 362,569.

To all whom 'it may concern:

Be it known that l, HERBERT E. Snannvn, residing at Newton, in the county .of Middle-- sex and State of Massachusetts, have inivhented certain Improvements in Circuit ySystems for Teli-phone Repeating Apparatus,

which .tlielollowing is a specification.

in telephone current reinforcing circuits in 'which tlie receivin element of the repeatin?r apparatus is supp ied With energy-from a bridlre connection across the main circuit, it has llieretofore'b'een necessary for satisfactory operation, to secure an approximate balance of electrical conditions in the line and. thus ,to avoid reactive disturbances in therepeating apparatus and a displacement between .the phase 'of the original and renewed voice currents.

The leading considerations in the present invention are the provision of suoli a bridged reinforcing circuit which is largely independ- Vent of the above noted conditions, and which,

when disturbed thereby, may be adjusted With a minimum effort on the part of the operator to overcome the effect of unbalance.

The accompanying drawings illustrate the invention, Figure 1 showing diagrammatically one embodiment in connection with a switchcord; lfig. Z a diagrammatic top plan view ofthe repeating induction coil; and Fig. 3 a simplified arrangement of the circuit of Fig. lwith the adjusting resistance differently dis Josed.

n all figures similar characters have reference to the same parts.

The invention is of particular utility when employed for successively connecting a number of lines having different elcctrical'propertics, since here is encountered not only a stato of unbalance, but also one in which the conditions may rapidly var v. Such service is required of repeaters situaledin the s'witclb cords used for joiningtoll lines; and Fig. 1 of the drawings presents schematically my improved circuit in a form adapted for this purpose.

'lhc letters d J2 designate jacks at a toll board in a station A, these having connected to' their tip and ring contacts, respectively, the line cond uclors ll if' and lj* li of metallic circuits leading lo other stations. and, when joined either conductively or4 indnctivclv, furnishing portions or sections of a transmit-4 ting circuit between these last named stations.

The sleeve contact of each jack is shown as grounded by a conductor 10. Cooperating With the jacks are plugs P P2 having their tips and rings connected by strands or conductors 11 and 12, respectively, belonginga to one of a plurality of cord circuits@ situated at a toll operators position. These cord conductors serve With the line conductors to complete the through transmitting circuit. From the sleeves of the jacks J and J2, res ectively, conductors 18 and 14 lead t rough the windings of relays 15 and 16 to the free ole of a battery B, the opposite poleof W ich is grounded. The purpose of these elements joined to the sleeves will be later described.

In the cord strands 11 and 12 are the primary windings of a repeating induction coil M which acts to deliver energy to the rein-l forcing circuit. This input coil, Which is shown in greater detail in Fig. 2, has said primary windings arranged in sections s' s2 s3 and si, of which s and s2 are in the conductor 11 with their terminals a; .r2 connected thereto, While sections s3 and s4 are in the conductor 12, which is joined to th'e terminais :t3 Q04. The other terminals y y2 and yt ofeach pair of sections are united and connected by a bridge conductor 17 containing a preferably variable resistance device O, this being illustrated as having an arm o lmovable over fixed contacts 02, between which vare the resistance coils 03. The primary sections of the coil M are Wound upon a magnetic core fm, common to all and to the secondary winding, which secondary, for the purpose of rendering the diagram more clear, is shown in Fig. 1 as having separate sections s s joined by a conductor 1S, and being particularlyT associated with the pairs of primary sections cs2 and s3 si, respectively. ln practice, however, as appears in Fig. 2, the secondary winding is continuous, the points ,s s (Fig. 1) coinciding; 'lhe terminals e and 2* of the secondary of the repeating induction coil are connected in the circuit 1S with the receiving` element l' of a suitable relay or repeating apparatus l, such as that disclosed in my Patents No. 791,655 and No. 791,656 of Julie (i, 1905. 'lhc trm'ismitting clement 'r'l of the repeater "is included in a circuit 20, which also contains a battery B2 and the primary Winding n of a transmitting inductionucoil N, the scctional secondary windings alZ of which are comprised in the co'rd strands' atl opposite sides of the bridge 17; This'coil N returns energy to the line, Ait being organized and adapted te operate as in my Patent.No;

791,656, previously referred to, and neednot be consideredv in detail. The -circuits 18 and 20, respectively, contain the normally se arated armature and front contact of the re ays. 16 and 15.

ln addition to the apparatus already. described, an operators set T is shown as bridged acrossthe cord in aconductor 2f, it being controlled by a key K. Animpedance 1 in series in the conductor 21-'p'revents' the operators circuit from takingv sc ijllmucli," rent as to sensibly affect the line'sectionwithv which the plugP connects the cord; i

The operation of the system v-is as follows In respon'sevto an order to connect the lines terminating in the jacks J J2, the operator selects the plugs P and Iz ofia cordcircuit not in use and inserts them in said jacks.

. Upon the connection of the plugs and jacks,

current flows from the battery -B through the relays 15 and-'16, conductors 13 and 14, plug sleeves and jack contacts to ground by conductors 10. `The relays thereupon. attracttlieir armatures'to complete the circuits 18 and 2() through both the'receiving and transmitting elements of the repeater.

The normally open condition of the circuits 18 and 20, until both plugs are in place, prevents the state of maximum'unbalance which would follow the connection ofthe repeating circuit to a single line section and which would produce a singing disturbance in the apparatus, and as res ects the circuit 20 the said open condition a so avoids Waste' of the battery B2 when the cord is not in use.

The normal position of the lever o of the resistance device O is upon its first contact, or that to the extreme right as seen in Fig. 1, the resistance of the bridge at such time being substantially zero, and we will assume 'that the present connection is between line I sections which, while not possessing the same electrical properties, arenot excessively ou-t 'of balance. 'Voice currents originated, for

example, at the station connected to the` lines l1 L2 "will flow through the cord conductor 11 and the primary section s of the coil M, and, on account of the absence of resistance in the bridge, will practically all pass therethrough, through the coil section s3 and back by conductor 12 to line. The

current in the primary sections s Jsj?-exercisea` an inductive effect upon the coml anion primary sections 52 and s4, as a resu t of which the voice currents are transmitted toa 'certain exteii`t-tlirectly through the cord into the line conductorsii and L4. These pairsA of primary windings are so connected that the current flowing in` both sections of each pair is neutralized as regards its eli'ect upon lthe' secondarywinding,` and therefore the upon the repeater.

"in the plpposite .direction through t s. f a

' any the' energy put u on the line by the secondary windings n2 o the transmitting induction coil, l the reinforcing currents do not react takes place from the opposite station, or that of the lines L3 L4, the general action is the same, the energizing current merely passing 'tion co I It will be seen that although, as in previous bridge repeating. circuits, the herein When transmission 1 e inducdescribed bridge connection presents a low impedance tendin to absorb current originated in either. ine portion, its passage through the repeating coil secures an important result not heretofore attained. For when the line sections are unbalanced a simple bridge connection between the opposite sides of the line, as in my Patent N o. 791,656, shunts through it practically all current put upon either section of the line, preventing an equalization thereof between said sections in absence of an adiustment of their electrical properties, as described in my Patent No. 835,037, dated November 6, 1906, and.

consequently causing the W'ell known reactive disturbances in the repeating ap aratus due to the presenceof a difference o potential at the extremitiesof the bridge. But,

with the repeating coil having cooperating windings in both ine sections, there 1s as- ;sured'atransfer of energy between them,

com ensating to a considerable extent for lack of balance and decreasing the `tendency of therepeater to sing. At the same time, this direct induction between primary windings situated in the line and the secondary Winding included in the reinforcing circuit, holds the voice currents transmitted from one to another without material alteration of phase, the common4 magnetic core i A aiding to preserve the definite relation. `It p isfalso found that this arrangement proves beneficial in lessening the absorption of ringingl'current by the bridge. It may be, h`ow.-

eveil that the character and dimensionsv ofthe :connected lines are such, that the above desdribed effect of automatic compensation through the repeating coil will not be su'liiif the repeater is found to be putting upon serbes' the 'line atonenofsueh strength as to objectionally affect" transmission, the lever o vis the bridge, decreasing the vand, capacity therefrom.

moved to graduallyintroduce resistance into flow therethrough and instead sending more current directly to line. Since, as has been before ointed out, only that portion passing throng the bridge acts u on the repeating circuit, it follows from tiis adjustment or regulation'of the current that the reinforcing action of the repeater and its sensitiveness to disturbance are proportionally reduced. rl his variation in the resistanceof the bridgeniay be continued until the efficiency of'transinission is at a maximum. While this results in a decrease of direct reinforcement, this action may still be more effectual than in systems in which the adjustment .of the values of the line sections is required, on account, in the present instance, of theremoyal of resistance Thou h this single adjustment throws but a slight burden u on the operator, it may be further facilitate by determining in advance the best values to employ with particular. lines, and this iriserted in the cord to be used before putting up the connection. rThis practice also avoids the creation of a disturbance in the repeateisov by the adjustin(T process? 1. c i lig. 3 of the drawings shows a Simp ified arrangement of the circuit, in which the piimary windings of the -re eating induction coil M and secondary Win(V ings of the transmittincf induction coil N are included directly in the line conductors L5 and L.- The relays are, therefore, omitted, as is the operators telephone circuit. The organization is other- Wise generally the same as that previously described, except that the variable resistance O2 is placed in the circuit with the receiving element of thc repeater instead of in the bridge. This, when used, decreases the seni sitiveness of the apparatus by a direct adjustnient, regulation; or cutting down of the current induced in the circuit of the receiving element of the coil M. it is found that a somewhat greater resistance is necessary to accomplish the same result than when itis placed in the bridge, but the effect is generally the saine. ln absence of the switchcord and associated operators set, it may be assumed that in this case the function of the resistance is to adjust the apparatus for more or less permanent use between the same pair' of line sections.

l claim as my invention:

l. In -a current renewing. system, `a line circuit having sections, a reinforcing circuit, an input coil for delivering energy from the line to the reinforcing circuit, and an. output coil for supplying renewed energy frointhe reinforcing circuit to the line, each of said coils having windings in lboth line sections i and in the reinforcing circuit, the line Wind- .cf theiiiiv'ut coil serving to inductively associate the iiiesections.

2. ln a current renewing'system, a line circuit having sections, a reinforcing circuit,l an input coil for delivering energy from the line to the reinforcing circuit, and an output coil for supplying renewed' energy from the reinforcing circuit to the line, each ofsaid coils having windings in both line sections and'in the reinforcing circuit, both the line windings and the reinforcing circuit Winding of the input coil being about a magnetic core magnetically common to all.

3. A telephone system'comprisinga transmitting circuit, a reinforcing circuit and apparatus associated with said transmitting circuit, and means for altering or changing the currentvvhich` the transmitting circuit supplies to the' reinforcing circuit and thereby varying the's'ensitivene's's of the reinforcing apparatus, said altering of the su plied current being other than or contra istinguished from variations therein corres ondingto transmitted speeclior sound; an( saidcurrerit Varying means o eratinv' independently of the electrical ba ance o the transmitting circuit.l

4. A telephone system comprising a transinittin circuit, a reinforcing circuit associated t erewithand-ineans for altering or changing the current supplied by the transmitting circuit tF the reinforcing circuit, said altering of the upplied current being other' than or contradistinguished-froin variations `therein corresponding to transmitted speech or sound, and said current varying means 0p- `eratin independently of the 'electrical balance o the transmitting circuit.

5. A telephone system comprising a transy mitting circuit, areinforcine circuit associated therewith, and means or adjusting or regulating the current supplied by the transmitting circuit to the reinforcing circuit, said current varyin means operating independently of the e ectrical balance of the transmit ting circuit.

6. A telephone system comprising a transinitting circuit, a reinforcing circuit associated therewith, a bridge iii the transmitting circuit through which current passes in reiidering the reinforcing circ-uit active, and. means associated with said bridge for varying the electrical impedance thereof. j

7. The combination with an electrical transmission circuit, of a reinforcing circuit, a bridge across the transmission circuit, said biid e being adapted to carry current for the supp y of energy to tlie'i'cinforcing circuit, and a variable resistance vconnected in the bridge.

8. The coiiihiiiatioi'i with a telephone line, of a repeating coil for delivering energy to the reinforcing. circuit hating pziiisef inductive'ly associated windings in cach side of The cooperating with 'the tine windings of the re- .ing

peeting coil, end e bridge connection between the sides ol' the line et points between the windings of each line pair of the repeatcoil. '9.V The combination with e telephone lino, of e repeating coil having pairs of associated windings in cach side of the line, a reinforcing circuit containing windings cooperating with the line 'windings of the repeating coil, .ell ol tire repeating coil windings being on :i

single magnetic core, irbridgc connection be tween the sides of the line et points between the windings of eacli line pair ol. the repent'- ing coil, undy en adjustable resistance in the bridge connection, subsenticlly as described.

l0. ln e telephone system, c cord circuit, telephone current reinforcing mechanism including two circuits, ineens connected` in the cord circuit for opening end closing one of seid reinforcing mechanism circuits, said ineens being controlled by the connection snddisconncction of one end of scid cord cir cuit with :i telephone line section, and other niennsconnected in the cord circuit 'for opening and closing tbn-other reinforcing incclienisi-n circuit, said other Ineens being controllcd by the connection and disconnection or" the other end-oi said cord circuit with c telepiicne line section.

l1. in e telephone system, :i cord circuit,

l cenone.

a telephone current repeater including two circuits, one a receiving clrcuit and the other a transmitting circuit, e; relay having its winding included in the cord circuit and its armature and e contact adapted to control seid receiving circuit, and a second relay heving its windlng included 4in the cord circuit and its armature and a Contact adapted to control seid transmitting circuit.

l2. The combination with a sectional line circuit, of s current reinforcing circuit, means for connecting the line sections, and means operable only upon the completion of the connection for closing the rein'lorcing caircuit.

13. The combination with s telephone line, of a. bridge connectio'n ecrossthe line, a coil having airs oi associated windings in erich side of me line, the windin s of each pair being at opposite sides of tlie ridge connection other and thus transmit current past the bridge, and n. reinforcinff circuit including HERBERT E. SHREEVE.

Witnesses:

Geo. WILLIS Pinnen, JOSEPH A. GATELY..

Vand being adapted to repeat into one anf 

